The present invention relates to a data updating system, navigation apparatus, server apparatus, and data updating method.
There exists data updating systems in which differential data is transmitted from a server to a terminal device, for example, a navigation device and terminal device that receives the differential data updates data using existing information already in its possession and the differential data. For example, the data updating system described in Japanese Patent Application Publication No. JP-A-2006-084257 is an information delivery system having a server that provides information and a terminal device that receives information from the server. The server has a differential information extracting section that extracts the difference between the information previously sent to the terminal device and the information to be transmitted, and a transmitting section which transmits the differential information extracted by the differential information extracting section to the terminal device. The terminal device has a receiving section that receives the differential information transmitted from the center equipment and a display section that displays the differential information received by the receiving section combined with the existing information.
In the case of traffic information, such as traffic jams and traffic controls, the differential information is the information which represents the difference between the previously produced traffic information and the latest traffic information. The terminal device which receives such differential information displays the newly received differential information combined with the existing traffic information that has been received and stored in its storing section. This configuration makes it possible to frequently update the traffic information to be displayed on the terminal device and to minimize the amount of data that is transmitted from the center equipment to the terminal device for updating.